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Atomic Force Microscopy of the Intervessel Pit Membrane in the Stem of Sapium Sebiferum (Euphorbiaceae)

Atomic Force Microscopy of the Intervessel Pit Membrane in the Stem of Sapium Sebiferum... Sapwood and juvenile wood of Sapium sebiferum (Euphorbiaceae) was collected during 2000 –2002. In air-dried vessel elements, the surface of pit membranes (PMs) in the outermost growth ring was coated with plaque-like or interstitial material that was 2–5 nm thick. This coating was phase dark and overlaid a phase bright layer of globules and reticulately arranged microfibrils (MFs) that was 25–50 nm thick. Beneath the reticulate layer there was another surface exposed during sectioning/fracturing. It had parallel MFs which appeared to be continuous with the middle lamella, and were also coated. The total thickness of the dried PM appeared to be in the range of 50–100 nm. Overwintering and heartwood PMs were encrusted with a non-microfibrillar layer that differed from the above mentioned coating. Prior to chemical treatment, specific dried, untreated PMs were located and then the sample was dismounted, treated with acidic H2O2, and observed after treatment so that before and after images could be compared. Treatment with acidic H2O2 removed some of the coating and greatly modified the fibrillar nature of the surface layer, but did not reduce its overall thickness. The native structure of sapwood PMs was observed in water. Non-dried PMs displayed two layers, each with a different type of surface. The outer layer was non-microfibrillar and covered the entire surface of the PM. The non-microfibrillar layer was extremely sensitive to mechanical perturbation by the AFM tip, and had phase characteristics similar to the coating of dried PMs. The underlying layer was thick and microfibrillar. The MFs in non-dried PMs were, like the dried MFs, phase bright but they were much more loosely intermeshed compared with those seen in dried materials. The measurable thickness (which does not represent the total thickness) of non-dried PMs frequently ranged from 90–225 nm, although a few 500 nm vertical features were measured. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png IAWA Journal Brill

Atomic Force Microscopy of the Intervessel Pit Membrane in the Stem of Sapium Sebiferum (Euphorbiaceae)

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Publisher
Brill
Copyright
Copyright © Koninklijke Brill NV, Leiden, The Netherlands
ISSN
0928-1541
eISSN
2294-1932
DOI
10.1163/22941932-90000124
Publisher site
See Article on Publisher Site

Abstract

Sapwood and juvenile wood of Sapium sebiferum (Euphorbiaceae) was collected during 2000 –2002. In air-dried vessel elements, the surface of pit membranes (PMs) in the outermost growth ring was coated with plaque-like or interstitial material that was 2–5 nm thick. This coating was phase dark and overlaid a phase bright layer of globules and reticulately arranged microfibrils (MFs) that was 25–50 nm thick. Beneath the reticulate layer there was another surface exposed during sectioning/fracturing. It had parallel MFs which appeared to be continuous with the middle lamella, and were also coated. The total thickness of the dried PM appeared to be in the range of 50–100 nm. Overwintering and heartwood PMs were encrusted with a non-microfibrillar layer that differed from the above mentioned coating. Prior to chemical treatment, specific dried, untreated PMs were located and then the sample was dismounted, treated with acidic H2O2, and observed after treatment so that before and after images could be compared. Treatment with acidic H2O2 removed some of the coating and greatly modified the fibrillar nature of the surface layer, but did not reduce its overall thickness. The native structure of sapwood PMs was observed in water. Non-dried PMs displayed two layers, each with a different type of surface. The outer layer was non-microfibrillar and covered the entire surface of the PM. The non-microfibrillar layer was extremely sensitive to mechanical perturbation by the AFM tip, and had phase characteristics similar to the coating of dried PMs. The underlying layer was thick and microfibrillar. The MFs in non-dried PMs were, like the dried MFs, phase bright but they were much more loosely intermeshed compared with those seen in dried materials. The measurable thickness (which does not represent the total thickness) of non-dried PMs frequently ranged from 90–225 nm, although a few 500 nm vertical features were measured.

Journal

IAWA Journal – Brill

Published: Jan 1, 2005

Keywords: Atomic force microscopy; cellulose microfibril; Euphorbiaceae; pit membrane; Sapium ; transpiration; vessel; wood structure; xylem

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